Human colon cancer is one of the most common malignancies in this country. The proposed investigations seek to chemically and immunologically characterize cell surface antigens distinctive of colonic neoplasia, and signals/receptor sites determining organoid differentiation. The applicants have previously initiated, established and characterized human colon cancer cell lines in tissue culture. Chemical studies comparing surface membrance profiles, as well as solubilized components of neoplastic versus normal colonic cells revealed numerous differences. The proposed studies will harness immunological tools to determine which of the altered proteins is distinctive of the neoplastic state. Monoclonal anti-colonic carcinoma antibodies produced by hybridization of myeloma (P3 x 63Ag8) with lymphoid cells derived from murine hosts pre-immunized with whole cell or soluble extracts of a variety of colonic neoplastic cell lines will be tested for a) immunological reactivity, detected by radioproline cytotoxicity assays and by immunoglobulin binding with SPA or antiglobulin, against a battery of colonic and other neoplastic cell lines as well as normal human lymphocytes, and adult and fetal normal colonic epithelium in continuous culture; and b) susceptibility to inhibition upon pre-incubation with antigenic fractions solubilized by 3M KCl and/or n-butanol and fractionated by preparative isoelectric focusing, lectin affinity chromatography and two dimensionsl polyacrylamide gel elctrophoresis. Normal colonic epithelial cell cultures will be established utilizing a combination of new isolation methods and application of proliferative stimuli of growth factors, insulin, hydrocortisone, polyamines, and gastrin. Colon cancer lines will be utilized to dissect factors responsible for organoid dfferentiation of neoplastic cells, utilizing the model of glandular formation on hollow fibers. These fundamental studies employing mon specific antibodies and purified cell components may afford insight into distinctive colon tumor antigens capable of triggering immune recognition, and being harnessed as immunodiagnostic and/or immunotherapeutic tools.